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glibc  2.9
s_frexp.c
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00001 /* Copyright (C) 1996, 1997, 2003 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <math.h>
00020 
00021 #ifndef FUNC
00022 #define FUNC frexp
00023 #endif
00024 #ifndef float_type
00025 #define float_type double
00026 #endif
00027 
00028 #define __CONCATX(a,b) __CONCAT(a,b)
00029 
00030 float_type
00031 __CONCATX(__,FUNC) (float_type value, int *expptr)
00032 {
00033   float_type mantissa, exponent;
00034   int iexponent;
00035   unsigned long fpsr;
00036 
00037   __asm ("ftst%.x %1\n"
00038         "fmove%.l %/fpsr, %0"
00039         : "=dm" (fpsr) : "f" (value));
00040   if (fpsr & (7 << 24))
00041     {
00042       /* Not finite or zero.  */
00043       *expptr = 0;
00044       return value;
00045     }
00046   __asm ("fgetexp%.x %1, %0" : "=f" (exponent) : "f" (value));
00047   iexponent = (int) exponent + 1;
00048   *expptr = iexponent;
00049   __asm ("fscale%.l %2, %0"
00050         : "=f" (mantissa)
00051         : "0" (value), "dmi" (-iexponent));
00052   return mantissa;
00053 }
00054 
00055 #define weak_aliasx(a,b) weak_alias(a,b)
00056 weak_aliasx (__CONCATX(__,FUNC), FUNC)